Classification societies: What they say about condition-based maintenance and condition monitoring

Written by: Tom Coleman, condition monitoring specialist at James Fisher Mimic

31 January 2022

Classification societies regularly update their guidance and recommendations on condition-based maintenance (CBM) to support organisations’ decision making when looking to gain value through the implementation of a CBM strategy.

They also provide succinct guidelines on how to achieve class notation for CBM and replace traditional planned maintenance with CBM for class maintenance surveys.

It is crucial to engage class when embarking on a CBM strategy and ensure traditional planned maintenance is suitable to be replaced by CBM, and find the correct balance between the two. At James Fisher Mimic (JF Mimic), we work with both the ship owner and class to ensure a successful outcome.

Below, we explore some of the major classification societies and what they say when it comes to CBM and condition monitoring (CM).


Last year, ClassNK released its CBM guidelines 2.0*. They have outlined the key differences between planned and condition-based maintenance, and the benefits that can be achieved when a shipping company adopts a CBM approach. These include:

  • Reduce periods of ship downtime
  • Prevent secondary damage
  • Reduce cost of repair parts
  • Reduce workload on crew
  • Avoid malfunctions unintentionally caused by planned maintenance work

Included within the guidelines are also some real-world examples based on studies of diesel engines and other critical machinery types.

*The published ClassNK guidelines can be downloaded free of charge via their website by those who have registered for the ‘My Page’ service.


DNV firstly focus on the drawbacks of traditional planned maintenance, such as:

  • Performing maintenance based only on predetermined intervals may result in unnecessary maintenance taking place
  • Unnecessary planned maintenance in isolation can introduce failures caused by human error. This results in reduced equipment reliability and increased downtime (out of service time).

DNV highlights the benefits of CBM, including:

  • Optimised maintenance function that only perform maintenance after a decrease in the condition of the equipment has been observed
  • A proactive maintenance approach provides better planning and control that avoids failures before they happen

Find out more on the DNV website.


Rina highlights how CBM can be an effective tool to adjust planned maintenance tasks, therefore improving the effectiveness of the overall maintenance strategy.

Another key point Rina makes is the cost effectiveness of a CBM approach is largely driven by the criticality of the machinery to be monitored. Check out our blog post, where we discuss this further.

Effective asset identification is a critical early stage to ensure the machinery that will benefit most from CBM is selected and the benefits of any maintenance development can be maximized.

Learn more here.

Lloyds Register

Lloyds Register (LR) launched a guide (2020) about CM techniques and CBM, which allows ship owners, operators, builders and designers to explore and take advantage of modern intelligence-led maintenance approaches.

LR has significantly updated its ShipRight procedures for machinery planned maintenance and CM and the corresponding rules, to embrace industry technological advances and owner operational needs.

Key changes include the introduction of risk-based maintenance to complement the existing reliability centred maintenance, and the introduction of new predictive technique approvals to meet a perceived shift towards digital twins, advanced data analytics and machine learning.

LR’s procedure enables operators to apply the most appropriate maintenance methodologies to each of their machinery items to suit their specific needs.

They go on to highlight the benefits of utilising a CBM strategy for ship owners and operators including:

  • Increase the availability and reliability of machinery while managing the risk of unpredictable breakdowns
  • Determine equipment condition and potentially predict equipment failure
  • Maritime organisations that use CM can experience less downtime, greater cost effectiveness of spare parts, and reduced overtime for responding to emergency breakdowns


JF Mimic is on hand to support the development of your CBM approach in collaboration with whichever classification society you partner with.

Classification societies are an important advisory when delivering CBM and will ensure key elements like effective machinery identification, and the correct implementation of a technology such as Mimic.

Get in touch with our condition monitoring specialists to discuss your CBM strategy.

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